The present invention relates to barrier movement operators and, more particularly, to such operators which respond to both rolling access codes and fixed access codes.
Automatic garage door openers comprise a door or barrier moving unit such as a controlled motor and intelligent activation and safety devices. The barrier moving unit is typically activated in response to an access code transmitted from a remote transmitter. RF signaling is the most common means of transmitting the access codes. It is important that the access code format transmitted by the remote transmitter is the same format as that expected by the receiver of the actuation equipment. A standard access code may, for example, comprise 20 digits which remain unchanged until the door opening equipment is reprogrammed. A possible security problem exists with fixed codes, since a potential thief might intercept and record a standard fixed access code. Later, the thief could return with a transmitter for producing an identical duplicate of the recorded code and open the barrier without permission.
Some garage door opening systems have begun using codes to activate the system which change after each transmission. Such varying codes, called rolling codes, are created by the transmitter and acted on by the receiver, both of which operate in accordance with the same method to predict a next access code to be sent and received. Rolling codes provide an improvement in the security of garage door operating equipment, however, they are more expensive than fixed code systems and most existing equipment is not of the rolling code variety. Additionally, since the transmitter and receiver each independently identify (predict) the next code based on the last code, it is possible that the transmitter and receiver will get out of sync with one another, requiring a reprogramming of the receiver.
Purchasers of new equipment may not believe they need the increased security of a rolling access code system and they may own older fixed access code transmitters which they would like to use with the new equipment. A decision to purchase fixed code systems may also be tempered by the concern about the possible periodic reprogramming which may be needed with rolling access code systems. Thus, consumers may want to purchase a fixed access code system. As time passes, the improved security of a rolling code system may appeal to them. The only avenue of change available to them is to purchase new rolling access code equipment. A need exists for a garage door operating arrangement which is capable of responding to either fixed or rolling access codes at the control of the owner. Were such an arrangement available, the owner would merely reprogram the receiver of his or her system and perhaps provide new code transmitters to achieve the security of rolling access codes.